Simon trained in general medicine then public health. Appointed Professor of Clinical Epidemiology in the University of Liverpool in 1999.

He manages a research programme spanning food policy and cardiovascular disease (CVD) prevention, with 300+ papers and £25 million funding thus far.

Simon is the UK Faculty of Public Health Vice President for Policy, a UK Health Forum Trustee and was SSM President 2014-15.

He has recently chaired/participated in a dozen national /international policy and prevention committees, including Academy of Medical Royal Colleges (Obesity), BHF, NICE (CVD prevention), European Society of Cardiology and WHO.